US3474593A - Method and apparatus for securing a relatively rigid header to a stack of flexible sheets - Google Patents

Description

Och 28.1969 E.A.HARTBAUE R'ETAL 3,474,593

METHOD ,AND APPARATUS FOR SECURING A RELATIVELY RIGID HEADER TO A STACK OF FLEXIBLE SHEETS 4 Sheets-Shefl Filed D60. 8. 1967 Oct. 28. 1969 E A. HARTBAUER ETAL 3,474,593

IBTHOD AND APPARATUS FOR SECURING A RELATIVELY RIGID HEADER TO A STACK OF FLEXIBLE SHEETS I Filed Dec. 8, 1967 4 SheetS-Sheet-Z 95 74 INVENTORS.

LLSWORTH A T AUER 86 E RUDOLF RH WEI FIG.5

ATTY.

Oct. 28. 1969 E. AQHARTBAUER ETAL METHOD AND APPARATUS FOR SECURING A RELATIVELY RIGID TO A STACK OF FLEXIBLE SHEETS Filed Dec. 8. 1967 HEADER 4 Sheets-Shet 4 Ihl 98 INVENTORS.

ELLSWORTH A HAR RU LF R. was BY I00 United States Patent M U.S. Cl. 53124 13 Claims ABSTRACT OF THE DISCLOSURE A tray receives a stack of flexible sheets with one end of the sheets overlapping one wall of an initially L-shaped header at the front end of the tray. Presser fingers adjacent the tray are actuated to compress the front end of the sheets, and then the other wall of the header is bent to shape the header into final U-shaped configuration with opposite walls of the header embracing the compressed end of the sheets and in position to receive fasteners through the header walls and sheets. Carriers for the presser fingers move the fingers in a compression direction perpendicular to the plane of the sheets; and, after compression, remove the fingers from beneath the other header wall in a direction parallel to the plane of the compressed sheets.

BACKGROUND OF THE INVENTION The present invention relates to a method and apparatus for securing a header to a stack of flexible sheets. While reference is primarily made hereinafter to the method and apparatus as relates to applying a header to a stacked group of plastic bags, it is to be understood that the invention also has application to applying headers, or the like, to other flexible sheets.

Bags formed of flexible plastic material, for example, polyethylene film, are becoming increasingly popular. The consumer, of course, purchases several bags at a time and it is therefore desirable to group the bags into which are easily handled prior to shipment to the consumer, and such groups of bags should be of such a nature as to facilitate removal of individual bags from the group as needed after the group is in the hands of the consumer. One manner of grouping which has been found desirable is by applying a relatively rigid header member to a stack of bags in such a manner that one end of the stacked bags is clamped between opposite walls of the header. Individual lines of weakeness in the bags at the end of the bags adjacent the header permit individual bags to be separated from the remainder of the stack. The header, in addition to adding rigidity to the stack, may provide a convenient means for receiving support brackets when it is desired to suspend the group of bags from a supporting surface. Because the stacked bags are fluffy due to entrapped air, and because the surfaces of the bags are quite slippery, it has been difficult to effectively and rapidly apply a header thereto while still maintaining the edges of the stacked bags in substantial alignment with each other.

SUMMARY It is, therefore, an object of the present invention to provide a method and apparatus which is useful in securing a header to a stack of aligned, flexible sheets, and which operates in such a manner that sheet edge alignment is maintained while the header is applied thereto.

Another object is to provide an apparatus Which effectively compresses one end of a stack of aligned, flexible sheets and holds such sheets in compression while the compressed end of the sheets receives a header in embracing relationship therewith.

. 3,474,593 Patented Oct. 28, 1969 Briefly stated, in accordance with one aspect of the present invention, a presser means is located adjacent a tray which receives a stack of aligned sheets. The presser is mounted and actuated in such a manner as to apply a compressive force to one end of the stack in a direction substantially perpendicular to the plane of the sheets so that entrapped air is forced out from between the sheets at the compressed end. This compression facilitates placement of a relatively rigid header in embracing relationship with the compressed end, and assures that sheet edge alignment is maintained while the header is properly placed. After the compressed ends are embraced by the header walls, the presser means is removed from contact with the sheets in such a manner that the header is not damaged. After removal of the presser means, appropriate structure acting through the header holds the sheet ends in compression between the header walls. Then, appropriate means is utilized to apply fasteners to secure the header to the sheets. In preferred form, the tray carrying the header-embraced sheets is moved to a fastener-securing position. To accommodate this movement, the tray is appropriately mounted on a trackway. If desired, though, the tray could remain stationary while the fastener-securing means is moved to the tray.

BRIEF DESCRIPTION OF THE DRAWING An embodiment of the present invention is illustrated in the accompanying drawings in which:

FIGURE 1 is a perspective view illustrating a stack of bags which has had a header secured thereto in accordance with the present invention;

FIGURE 2 is a partial perspective view of the apparatus of the present invention;

FIGURE 3 is a plan view, mostly diagrammatic with parts broken away, of apparatus embodying the present invention;

FIGURE 4 is a front view, mostly diagrammatic with parts broken away, taken on line 44 of FIGURE 3, and illustrating respectively by solid and phantom outline, a first and second position of presser means;

FIGURE 5 is an enlarged sectional view of a presser finger and arm used in the presser means of this invention;

FIGURE 6 is an enlarged sectional view taken on line 66 of FIGURE 3, with the tray in a stack-receiving position and presser fingers in compressing position, and with parts broken away for clarity;

FIGURE 7 is a still further enlarged sectional view similar to FIGURE 6, but with the tray in a fastenersecuring position;

FIGURE 8 is an enlarged view taken on lines 88 of FIGURE 6 with parts broken away for clarity; and,

FIGURE 9 is a view taken on line 99 of FIGURE 7, with the stapler removed and parts broken away for clarity.

DETAILED DESCRIPTION In order to better understand details of the apparatus and method of operation of the present invention, a description of which is to follow, it may be helpful to describe an exemplary form of a bag stack which has had a header applied and secured thereto in accordance with the present invention. In this regard, and referring to FIGURE 1, there is illustrated a stack 15 of aligned bags. The bags are flexible and, by way of example, each has opposite walls which may be formed of 1.1 mils polyethylene. As illustrated, a transverse seal line 16 joins the opposite walls of each bag together to form a bottom for the bag near one end thereof. Near the opposite end, a transverse line of weakness 17 in the form of perforations facilitates removal of an individual bag from the remainder of the stack, as desired.

A generally U-shaped header 18 embraces one end of the bag stack. The header serves as a medium to 30m all of the bags together, such as by inserting fasteners 19 in the form of staples through opposite header walls 20 and 21 and through the end of the bags embraced therebetween. More accurately, the portions of the bags receiving the staples are above the lines of perforations, so that these staple-receiving portions are separated from the bags when an individual bag is removed from the stack. The header may also serve to receive a bracket in supporting a stack of bags from a mounting surface. For example, the header could be mounted by having legs in a U-shaped metallic wicket (not shown) received in grooves 22 and 23 in the header; the wicket, of course, being secured to the mounting surface. To adequately perform a supporting function, the header is preferably formed of a relatively stiff or rigid material as compared to the material of the bags. Cardboard or other stiff material may be used. Score lines 24 and 25 define the walls of the header and facilitate bending the header from an initial planar construction to the final substantially U-shaped configuration.

Platform As seen in the drawings, and particularly FIGURES 2 and 6, a rigid platform is utilized which provides supporting and mounting surfaces for the operating members of the apparatus. While particular structural elements have been illustrated in the drawing, and as will hereinafter be described, as formnig a suitable platform structure, it will be understood that any suitable platform or frame support may be used which will adequately support the operating elements at their proper working position.

The illustrated platform includes a horizontally extending front frame member 26 having an upper surface 27 and which is supported from the ground or floor by appropriate vertical frames 28 (FIGURE 6). Also, as seen at FIGURE 6, a rear frame member 29 is spaced from and extends generally parallel to the front frame member 26 at a slightly higher vertical elevation than the front member, and the rear member 29 may also be supported from the floor by vertical frames. A rigid plate 30 extends in a horizontal plane between the frame members 26 and 29. The plate has a vertical leg 31 near the front end thereof which may be secured to the member 26 such as by welding. The plate 30 is also secured to the rear frame 29, and this may be accomplished by welding or, if desired, removable fasteners may be used to fasten the plate to the frames at opposite ends of the plate. A working table 32 for the operator may be secured to the rear frame member 29.

In order to provide a trackway, for reasons which will be described later in detail, a pair of vertical walls 33 and 34 have their bottom edges abutting and firmly secured to the upper surface of plate 30. The walls 33 and 34 are spaced a predetermined distance from each other and extend in a direction parallel to the side edges 35 and 36 of plate 30. Surfaces 37 and 38 (FIGURE 8) defining the trackway are formed by cutting or otherwise forming longitudinally extending grooves in the outer surface of each wall. As seen most clearly at FIGURE 6, the trackway 37 in wall 33 has a relieved portion 39 near the front end thereof which extends below the remaining portion of the trackway. The trackway 38 also has an identical relieved portion 40 directly across from the relieved portion 39. Suffice it to say now that these'relieved portions cooperate with trackway followers in such a manner as to permit receipt of a header-embraced stack of bags between the hammer and anvil of a stapler without scraping the outer wall of the header.

Carriage and tray A tray 41 is movably mounted on the platform through the medium of a carriage 42, the tray extending above and being fixedly secured to the carriage. The carriage is mounted for movement along the trackway surfaces 37 and 38.

Referring especially to FIGURES 2, 6, 7 and 8, it is seen that the carriage comprises atop wall 43 and spaced, downwardly-extending vertical side walls 44 and 45. Each of the side walls has trackway follower elements mounted thereon for movement along the trackway surfaces 37 and 38. In further description of the follower elements, it is seen that the Wall 44 carries front and rear rollers 46 and 47, respectively, each of which rollers extends inwardly of the side wall 44 and is supported for rotation from the side wall. The side wall 45 also has front and rear rollers extending inwardly thereof (only the front roller 48 appearing at FIGURE 8) and it is to be understood that the rollers on wall 44 are directly across from corresponding rollers on wall 45. The front rollers 46 and 48 are spaced apart from each other a distance such that roller 46 will ride on trackway surface 37, and roller 48 will ride on trackway surface 38. The rear rollers are also spaced the same distance apart from each other so as to be supported on their respective trackway surfaces.

In order to provide further lateral stability to the carriage with respect to the platform walls 33 and 34, surfaces 49 and 50 on the carriage walls (FIGURE 8) are in sliding contact with respective walls 33 and 34 below the trackway surfaces, and lubrication fittings 51 are used to provide lubricant to surfaces 49 and 50 to reduce the friction. Other lubrication fittings 52 extend axially outwardly of the rollers 46 and 48 and provide a flow path for lubricant to be introduced to the bearings supporting the rollers.

In further description of the carriage 42, a vertical center wall 53 extends downwardly from a horizontal wall 54, and the wall 53 is received in the space between plat form walls 33 and 34 when the carriage is mounted on the platform. The wall 53 serves as a means for securing a suitable actuator 55 to the carriage for moving the carriage along the trackway. In preferred form, and as is perhaps clearest at FIGURE 6, the actuator 55 is pneu matic and includes a piston-cylinder structure 56. The rear end 57 of the cylinder is pivotally secured at 58 to the plate 30 behind the carriage. It is to be understood that a piston (not shown) has an arm which is connected to the wall 53. When pressurized air is introduced through inlet 59, the carriage 42 is moved frontwardly (from left to right as viewed at FIGURE 6) along the trackway. When the pressure on the fluid is released, a tension spring 60, having one end attached to the carriage 42 and the other end attached to frame member 29, returns the carriage to its initial position.

The tray 41 includes a bottom wall 61 and opposed side walls 62 and 63. The side walls of the tray are flared outwardly along the upper edges thereof to facilitate placement of bags in the tray during a stacking operation. The distance between the side walls 62 and 63 is only slightly greater than the distance between opposite side edges of bags which are to be received therein. If desired, the Walls could be made laterally adjustable so as to effectively accommodate various sized bags in the tray. The tray 41 further includes a forward or front end in the form of an extension 64 which has a recessed portion 65 therein, the recessed portion being dimensioned to receive one leg of a header 18 in a manner to be described later. The tray 41 is secured to the carriage 42 by welding or otherwise securing the extension 64 to an upper plate 66 which has been secured to the top wall 43 of the carriage. As seen most clearly at FIGURE 6, the bottom wall 61 of the tray preferably has a slight upward slope from front to rear to facilitate proper placement of bags therein.

Presser means Presser means 67 form an important part of the present invention. In order to better understand the function performed by the presser means it may be helpful, at this point, to describe a part of the operation which is accomplished with the use of the structural member which have already been described. In this regard, it may be noted that the position of the tray 41 as illustrated at FIGURES 2, 3, 4 and 6 is considered to be the stack-loading position. The tray position of FIGURE 7 is the fastener-securing position. With the tray in the stack-loading position, one wall 20 of a cardboard header 18 is placed in the recessed portion 65 of the tray at the forward end of the tray, the header having been bent along score line 24 so that the other wall 21 of the header extends vertically upwardly. Now, a stack of flexible plastic bags 15 is positioned in the tray so that the front end of the bags overlaps the header wall 20, the edges of the bags being in substantial vertical alignment with each other. The bags have, however, trapped air between opposite surfaces, and a stack of, for example, 120 bags having walls of 1.1 mils polyethylene is around 2 /2 inches high. If it were attempted to embrace the top end of the bags by folding header wall 21 over the end of the bags without first compressing the bags, problems would occur because the movement of the wall over the bags would tend to displace the bag edges out of alignment with each other. Such displacement, in addition to having a disadvantage of providing a package of poor appearance, may misalign the bags a suflicient distance so that fasteners (such as staples) which are ultimately applied do not occupy proper placement in the bags. It has therefore been found that it is necessary to compress the end of such a stack prior to embracing this end between the header Walls.

In preferred practice of the present invention, the presser means structure which is utilized for providing the compression just mentioned may be visualized by referring to FIGURES 2-5. There, it is seen that a support leg 68 has one end 69 pivotally connected to the front frame member 26, and the free end 70 of leg 68 is spaced vertically upwardly from the pivotal connection. An arm 71 is connected to the free end 70 of leg by a pivot pin 72 which forms a pivotal axis for the arm so that the arm 71 will move with the leg 68, but the arm 71 is also capable of its own pivotal movement with respect to the leg 68. A pair of opposed side plates 73 and 74, and a top plate 75 form extensions on the end of the arm 71 nearest the tray 41, and these extensions may be secured to the arm proper such as by welding. The remote end 76 of the arm 71 extends on the opposite side of the supporting leg 68 from the tray 41, and one end 77 of a biasing means in the form of a tension spring 78 is attached to this remote end. The other end of the tension spring 78 is attached to an ear 79 on leg 68, and the spring is in tension to con tinually urge the remote end 76 of the arm toward the leg 68.

A flat presser finger 80 is pivotally connected to the arm 71 by a pivot pin 81 which passes through the side plates 73 and 74 and through an extension 82 on one end of the presser finger. The presser finger 80 thereby moves with the arm 71 and leg 68, but is capable of its own independent pivotal movement with respect to the arm 71. As seen at FIGURE 5, a tension spring 83 is connected to the extension 82 and to the arm 71 to urge the extension on the presser finger into abutment with top plate 75. Further, an adjustable stop means is provided which limits the pivotal movement of the presser finger 80' against the bias of spring 83. This adjustable stop comprises a bolt 84, which passes through an opening in the extension 82 and is threaded through a nut 85 secured to the top surface of the extension. The head of the bolt engages a stop plate 86 extending between opposite side plates 73 and 74, when the presser finger 80 has pivoted a predetermined distance with respect to the arm 71.

Actuator structure in the form of a first actuating means 87 and a second actuating means 88 is provided in order to enforce desired motion on the presser finger 80 through the medium of the leg 68 and the arm 71.

The first actuator means 87 comprises a piston-cylin der arrangement, and one end 89 of the cylinder is pivotally connected to the front frame member 26. A piston rod 90 is connected to a piston within the cylinder, and the outer end of the piston rod is pivotally connected to an ear 91 forming a part of the leg 68 intermediate the opposite ends of the leg. When the piston rod 90 is at its extreme inner position, the leg 68 will be at the position of FIGURE 2, and when the piston rod is at its extreme outer position, the leg will have been pivoted to a position farther away from the tray 41.

The second actuating means 88 also includes a pistoncylinder arrangement wherein one end 92 of the cylinder is pivotally connected to the front supporting frame member 26. One end of a piston rod 93 is connected to a piston within the cylinder, and the other end 94 of the piston rod is pivotally connected to the arm 71 by a pivot pin 95 extending through opposite side plates 73 and 74 on the arm and through an opening in the end of the rod. It is movement of the rod 93 into its associated cylinder that carries the presser finger 80 into compressing position on the bags as will be pointed out hereinafter in greater detail.

The part of the presser means which has just been described, and which is illustrated in full at FIGURE 2, is operative to compress one side of the front end of bags which have been positioned in the tray. Identical means are mounted on the other side of the tray for compressing the other side of the bag, as illustrated somewhat sche matically, but in full outline, at FIGURE 4. Inasmuch as the presser means which operates on each side is identical, the same reference numerals for corresponding parts have been used, except that the addition of a figure prime has been used with respect to the presser parts illustrated in full at FIGURE 4. No additional specific description of the presser which operates on the right side (as viewed at FIGURE 2) of the stack of bags is deemed necessary.

Operation of the presser means As has already been described, a header 18 may be loaded into the tray and then a stack of bags may be positioned therein in overlapping relationship with one wall 20 of the header. Initially, and while the tray is being loaded with the header and bags, the presser means 67 and 67 is at the solid line position of FIGURE 4. At this solid line position, air under pressure has been admitted to inlets 96 and 96' respectively on the first actuating means 87 and 87' to move the legs 68 and 68' to their extreme outer position with respect to the tray. Once the stack of bags has been aligned in the tray, the pneumatic pressure on inlets 96 and 96 is released. Such release of pressure causes the legs 68 and 68' to pivot from the solid line position of FIGURES 4 and 3 to the position of FIGURE 2. This pivoting in part is aided by spring 78 attempting to achieve a relaxed position, and in part by the weight of the arm 71 on the side of the pivot 72 between the pivot 72 and the tray 41.

When the presser fingers 80 and 80 have reached the position of FIGURE 2, they are immediately above the end of a stack of bags to be compressed, and they are ready to be moved in a manner to exert the required compression. This movement is accomplished by introducing air under pressure into inlets 97 and 97' in cylinders 88 and 88' respectively, which causes the piston rods 93'and 93 to be forced into the cylinders (along with the piston). The rods carry arms 71 and 71' with them and cause the arms to pivot relative to legs 68 and 68'. During the downward movement of rods 93 and 93, the presser fingers 80 and 80 will contact the uppermost sheet in the stack before the rods have reached their extreme downward position. Or, in other words, the sheets may be said to exert an upward reaction force on the presser fingers during the time of contact of the fingers with the sheets. As soon as this force becomes great enough to overcome the bias of springs 83 and 83, the presser fingers 80 and 80 began pivoting with respect to the arcs 71 and 71' against the bias of springs 83 and 83' so that the presser fingers remain in substantially full contact with the end of the uppermost sheet in the stack, and during compression, the presser fingers apply a compression force which has a substantial component in a direction perpendicular to the plane of the sheets or bags.

Once the rods 93 and 93 have been withdrawn to the innermost position in their respective cylinders, the presser parts will occupy the position illustrated in phantom outline at FIGURE 4. Now, the front end of the sheets or bags have been compressed from a height of, for example, 2 /2 inches to a height of inch, and the edges of the sheets are still in vertical alignment with each other.

While the above operations have taken place, the tray 41 has remained in a rearmost or stack-receiving position. Still other operations, now to be described, are performed while the tray is in this position. First, a suitable header guide member is actuated (the preferred structure of which will be described later) to bend the wall 21 of the header into embracing relationship with the compressed end of the bags, and this movement of the header wall 21 also sandwiches the presser fingers 80 and 80 between the bags and the header wall 21. Then, the presser fingers must be removed from beneath the header wall 21 while the header guide member is holding the wall 21 in embracing relationship with the compressed ends of the bags. Removal of the presser fingers from beneath the header wall is accomplished by removing the air pressure from inlets 97 and 97', and by admitting air under pressure into inlets 96 and 96'. This causes the legs 68 and 68' to pivot in a direction away from the tray 41. However, because of the pivotal connection between the presser fingers 80 and 80 and arms 71 and 71, the fingers will, in moving from beneath the header, slide along the uppermost sheet in a direction substantially parallel to the plane of the sheet or bag surface until the ends of the fingers have cleared the header. Once the presser fingers are clear of the header, springs 78 and '78, and springs 83 and 83' will return the presser fingers and arms to their initial solid line position of FIGURE 4, thus completing the cycle and having the presser means in readiness for another cycle. After the presser means has returned to the solid line position of FIGURE 4, the tray 41 with the stacked sheets having one end compressed, and now embraced by the header guide member between opposite walls and 21 of the header, may be moved forward to a fastener-securing position. During r Header guide member Referring especially to FIGURES 2, 6 and 8, it is seen that the header guide comprises a generally U-shaped member 98. Pivot pins 99 and 100 extend through legs 101 and 102 of this member 98 approximately midway of the length of the legs, and the pivot pins pivotally attach the member 98 to an upstanding bar 103 on the forward end of the tray extension 64. The base 104 of the member 98 functions as a bender bar and extends across and above the front end of the tray. The side of the bender bar 104 facing the tray has a generally L- shaped abutment 105 (FIGURE 6) secured thereto. This abutment is at such a level above the recessed portion 65 in the tray that the edge of upstanding wall 21 of the header will fit therein to aid in proper initial placement of the header. Connector bars 106 and 107 are secured to the ends of the legs 101 and 102 opposite from the bender bar 104. The connector bars extend toward the opposite sides 44 and 45 of the carriage and permit connection of the bars to suitable actuator structure mounted on the carriage. The actuator structure just mentioned comprises a pair of cylinders 108 and 109 having rear ends which are pivotally secured to respective carriage sides 44 and 45. A piston is mounted in each cylinder, and rods 110 and 111 are connected to respective pistons for movement therewith, the rods extending out of the ends of the cylinders opposite from the ends Where the cylinders are connected to the carriage Walls. The outer ends of the rods 110 and 111 are pivotally connected to respective ends of the connector bars 106 and 107.

In operation, with the parts initially in the position of FIGURE 6, pressurized air is admitted to inlets 112 and 113 in the rear cylinders 108 and 109. This forces the piston rods 110 and 111 outwardly which causes the bender bar 104 to pivot in a direction toward the tray 41 carrying the upstanding wall 21 of the header with it into the overlapping or embracing relationship with the compressed end of the bags 15 in the tray. As mentioned above, the bender bar 104 holds the header in contact or clamping position with the uppermost sheet in the compressed end of the sheets while the presser fingers 80 and 80' are slid from beneath the header wall 21. Then, after the presser fingers are removed, the tray 41 and bender bar 104 are moved forwardly as a unit from the stack-receiving station of FIGURE 6 to the fastenersecuring position of FIGURE 7 with the bender bar exerting sufficient force to hold the bags in compression. Such movement is accomplished, of course, by admitting air under pressure to inlet 59 in cylinder 56. An adjustable abutment in the form of a bolt 114 threaded through a nut 115 secured on platform wall 33 provides a positive stop for the carriage at its forward position by engagement of the bolt with roller 46 when the roller has reached its extreme forward position. Similarly, an adjustable abutment 116 provides a positive stop for rearward travel of the carriage 42.

Carriage-biasing means As mentioned previously, the trackway surfaces 37 and 38 have relieved portions 39 and 40 (FIGURES 6 and 8) near the forward end thereof. These relieved portions permit the carriage 42 to co-act with a pivotable carriagebiasing means 117 in such a manner as to assure proper placement of fasteners or staples through the header and bags. Before discussing the particular biasing means, however, reference should be made to FIGURE 7 which illustrates the tray 41 at a fastener-securing position. There, it is seen that opposite walls 20 and 21 of the header, with the compressed ends of the bags sandwiched therebetween, have received a fastener 19 in the form of a staple, from a stapling machine 118. This stapling machine per so may be conventional, and so it has been illustrated only in phantom outline. Suffice it to say, however, that the stapling machine will have an ordinary stationary anvil 119 and a movable hammer 120, which hammer forces staples through the header walls and against the anvil to bend the staples. To perform properly, the bottom surface of the header wall 20 must contact the anvil 119. When it is realized, however, that the header is inserted from the front between the anvil 119 and hammer 120, it can be appreciated that if the header wall, at its point of initial insertion, were to contact the anvil, the anvil may scrape the header wall and cause damage thereto. Therefore, it is desirable to have the header inserted in such a manner that the header wall 20 will clear the anvil until the movement of the header has reached its stapling or fastener-securing position. Then, the header, or more accurately, the tray 41 and carriage 42, should be capable of limited pivotal movement to bring the header wall 20 into contact with the anvil 119.

Establishing a clearance between the anvil 119 and the header, as the header is inserted between the anvil and hammer, is accomplished by utilizing a carriage-biasing means now to be described. As is clearest at FIGURES 2, 6 and 8, a horizontal plate 121 extends beneath the platform plate 30, and the plate 121 has side walls 122 and 123 which permits pivot pins to be inserted therethrough to pivotally connect the plate to leg 31 of plate 30. The downward vertical position of the rear end 124 of plate 121 is adjustably fixed by a bolt 125 which extends through the plate 121 and is threaded into a threaded aperture in platform plate 30. A compression spring 126 urges the plate 121 against the head of the bolt 125; however, the opening in plate 121 which accommodates the bolt is large enough to permit upward pivotal movement of the rear portion 124 of plate against the bias of compression spring 126. A pair of rollers is supported from the plate 121 at the front end thereof on the opposite side of the pivot from the spring 126. These rollers 127 and 128 are at such vertical level as to contact the bottom surfaces 129 and 130 of the carriage walls 44 and 45 and support the carriage so that the front carriage rollers 46-and 48 are at the level of trackway surfaces 37 and 38 (and above the level of the relieved portions 39 and 40) when the front rollers reach a position immediately above the relieved portions. When the front rollers 46 and 48 are above the relieved trackway portions 39 and 40, the wall 20 of the header 18 is above the anvil 119 and in staple-receiving position. When the hammer 120 is lowered, however, the force of the hammer causes the rollers 127 and 128 to pivot downwardly about the pivotal axis connecting the plate 121 to the platform leg 31, and this movement is tolerated by the carriage because the front rollers 46 and 48 on the carriage can move downwardly onto surfaces 39 and 40' of the relieved portion. In operation, when the hammer applies a staple, the carriage itself is caused to pivot slightly about an axis defined by the axis of the rear rollers supporting the carriage.

As seen at FIGURE 1, two staples 19 are applied. This may be accomplished by using two stapler units or by using one unit in a manner such that first one staple is applied and then the unit is shifted laterally to a proper position to apply a second staple.

Summary of operation While operation of the apparatus of the present invention has been set out in connection with particular components thereof, it may be helpful to summarize the operation of the entire apparatus.

First, a header wall 20 is positioned in recessed portion 65 of the tray 41, with the edge of the other header wall 21 contacting abutment 105 on the bender bar 104. Then, a desired number of bags are stacked in the tray so as to overlap header wall 20. Up to this point, the presser means 6-7 and 67 has been in a first or solid line position of FIGURE 4. Then, by suitable actuation of the first and second actuator means 87, 87', 88 and 88' which operates the presser fingers 80 and 80', the presser fingers are actuated to apply compression force to the ends of the bags overlapping the header in a direction substantially perpendicular to the plane of the bags. After compression of the bags, the bender bar 104 is actuated to bend header wall 21 into embracing relationship with the compressed bags, and then the presser fingers 80 and 80', the tray 41, carriage 42 and bender bar 104 structures are moved as a unit to a fastener-securing position where staples are inserted through the header and through the compressed end of the bags. The tray 41 is then returned to its initial stack-receiving position, the bender bar is raised by admitting air under pressure to inlets 112a and 113a at the front end of cylinders 108 and 109, and the stack with a header secured thereto is removed from the tray.

If it is desired to completely automate the device, the flow of pressurized air to the various cylinders at the proper time may be regulated by a rotary switch or any suitable programming means. Alternately, of course,

operation of the cylinders need not be automated but could instead .be individually controlled by an operator so long as they are operated in the sequence set forth above.

While the foregoing specification has set forth an embodiment of the present invention in considerable detail for purposes of making a complete disclosure thereof, various other embodiments and modifications will occur to those skilled in the art, but will fall within the spirit and scope of the invention defined in the following claims.

What is claimed is:

1. In an apparatus for securing opposite walls of a generally U-shaped header in embracing relationship with one end of a stack of flexible sheets by insertng fasteners through said header and sheets wherein the improvement comprises:

(a) a tray mounted on a platform and adapted to receive the flexible sheets in stacked, aligned relationship;

(b) presser means mounted on the platform and movably positioned with respect to the tray, said presser means being operable for movement between a first position where said presser means is free of the stacked sheets and a second position where said presser means applies compressive force to one end of the sheets to compress the sheets in a direction substantially perpendicular to the plane of the sheets, and actuator structure operably connected to the presser means for actuating said presser means between said first and second positions; and,

(c) a header guide member supported from the platform and operable to embrace the compressed end of the sheets between opposite walls of the header and hold the walls in embracing relationship with the sheets while the fasteners are applied thereto.

2. The apparatus as set forth in claim 1 wherein said presser means includes a pair of presser fingers, and said actuator structure includes first and second actuating means; the first actuating means being operably connected to said presser fingers for moving the fingers from said first position to an intermediate position immediately above the end of the sheets to be compressed, and for returning said presser fingers to said first position; the second actuating means being operably connected to said presser fingers for moving the fingers from said intermediate position in a direction having a component perpendicular to the plane of the sheets to compress the sheets.

3. The apparatus as set forth in claim 2 where the header is initially substantially L-shaped, including one wall overlapped by the sheets with the other wall upstanding, and wherein said header guide member includes a bender bar operable to bend said other header wall over the compressed end of the sheets, and actuator structure for operating the bender bar.

4. The apparatus as set forth in claim 1 wherein said tray is secured to a carriage, the carriage is movably mounted on the platform, and the apparatus includes means for moving the carriage between a stack-loading position and a fastener-securing position.

5. The apparatus as set forth in claim 4 wherein said tray includes a forward end adapted to receive the stack of sheets in overlapping relationship with one wall of the header when the header is initially L-shaped in cross section with the other wall of the header upstanding, and wherein said header guide member is secured to the carriage for movement therewith, and the guide member includes a pivotable bender bar operable to bend said other wall of the header into contact with the uppermost sheet in the stack while said sheets are compressed.

6. The apparatus as set forth in claim 1 wherein said presser means includes a pair of support legs pivotally connected to the platform for movement toward and away from each other; an arm pivotally connected to each of the legs for movement therewith; a presser finger for compressing said sheets pivotally attached to each of the arms, said fingers extending toward each other generally parallel to and initially above the plane of the sheets and forming extensions on the ends of each of said arms; first actuator means connected to each of said legs for pivoting said legs to move said fingers toward and away from said sheets in a direction substantially parallel to the plane of the sheets; and second actuator means connected to each of said arms for moving said fingers in a direction substantially perpendicular to the plane of said sheets to compress the sheets.

7. The apparatus as set forth in claim 1 wherein said tray includes a front end having a recessed portion for receiving one wall of said header; said header guide member includes a movable bender bar extending above said recessed portions; and means for actuating said bender bar to bend the other wall of the header from an initially upstanding position to a position overlying the compressed end of the stack.

8. The apparatus as set forth in claim 7 wherein said bender bar includes an abutment for contacting the free edge of said other wall in upstanding position to facil itate proper placement of said header.

9. The apparatus as set forth in claim 4 wherein the platform includes surfaces defining a trackway for supporting trackway follower elements on the carriage between the stack-loading position and the fastener-securing position; the trackway including a relieved portion at the fastener-securing position, said relieved portion extending below the remaining portion of the trackway; and movable biasing means for initially supporting the carriage at the level of the remaining portion of the trackway when follower elements are above the relieved portion, the biasing means being movable downwardly to permit said carriage and follower elements to move downwardly in said relieved portion when fasteners are secured through the stack.

10. The apparatus as set forth in claim 9 wherein said carriage includes opposite sides, and said trackway follower elements include front and rear rollers mounted on each of said sides, said front rollers being receivable in said relieved portion, and the carriage being pivotable about the axis of the rear rollers when the front rollers are received in said relieved portion.

11. Apparatus for compressing one end of a stack of aligned sheets of flexible material preparatory to applying a header to the sheets, said apparatus comprising:

(a) a tray for receiving the sheets;

(b) a pair of support legs pivotally connected to a platform at locations spaced respectively from opposite sides of the tray, the legs each having a free end spaced vertically upwardly from the pivotal connection of the leg to the platform;

(c) first actuator means connected to each of the legs for pivoting the legs toward and away from the y;

(d) an arm pivotally connected to each of said legs, said arms each having a remote end extending on WAYNE A. MORSE,

12 the opposite side of a respective supporting leg from the tray;

(e) a presser finger pivotally connected to each of the arms at the end opposite from the remote end, said fingers extending toward each other and being movable between a first position spaced above the tray and a second position where the fingers compress sheets when sheets have been stacked in the tray;

(f) spring means connected to each arm and a respective presser finger for biasing said arms toward said first position; and,

(g) second actuator means connected to each of said arms for pivoting said arms in a direction toward the tray, said pivotal connection between the arm and presser finger permitting each said presser finger to pivot relative to a respective arm against the bias of said spring means when said second actuator means pivots the arms toward the tray to cause the presser fingers to exert a compression force on sheets in the tray, said compression force having a substantial component in a direction perpendicular to the plane of the sheets.

12. The apparatus as set forth in claim 11 wherein an adjustable stop means is provided for limiting the pivotal movement of the presser fingers during compression of the sheets.

13. The apparatus as set forth in claim 11 which further includes a biasing means for continually biasing the remote end of each arm toward its respective leg.

References Cited UNITED STATES PATENTS 773,484 10/ 1904 Drucklieb 931 1,824,506 9/ 1931 Schramm 114 2,667,997 2/1954 Vogt 53137 2,671,587 3/1954 Vogt 53137 2,671,588 3/1954 Vogt 53137 2,745,233 5/ 1956 Collings 53-138 3,022,620 2/ 1962 Gallet 53137 3,367,085 2/ 1968 Parsons 9335 3,380,579 4/1968 Pinto 9335 3,387,542 6/1968 Gartner 931 3,161,347 12/1964 Hannon 9336 X 3,260,516 7/ 1966 Blair 270-37 X 2,076,435 4/ 1937 Nelson 53-196 X 3,255,679 6/1966 Eckels 9336 FOREIGN PATENTS 157,636 7/ 1954 Australia. 1,214,194 4/1966 Germany. 1,217,919 6/1966 Germany. 1,090,245 11/ 1967 Great Britain.

JR., Primary Examiner U.S. Cl. X.R.

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